A model for current oscillations in the Si-HF system based on a quantitative analysis of current transients

With sufficiently large applied anodic potentials, the dissolution of silicon in fluoride electrolytes causes current oscillations that are correlated with an anodic growth of silicon oxide. The dynamics of oxide growth and dissolution is studied by transient current measurements at various phases of the oscillation. An interpretation of the transient currents as a direct representation of the oxide thickness distribution allows the calculation of the oxide capacity, showing excellent quantitative agreement with in situ FFT impedance measurements. The analysis of an averaged continuity equation yields absolute values for dissolution rate and oxide thickness and provides components for an oscillation model. The physical character of local oscillators on a nm scale will be outlined. Next-neighbor coupling leads to percolation areas of about 100 nm as result of Monte Carlo simulations. The percolation provides an intrinsic synchronization mechanism leading to macroscopic oscillations.